Calcium handling abnormalities increase arrhythmia susceptibility in DMSXL myotonic dystrophy type 1 mice - 08/11/24
Abstract |
Background |
Myotonic dystrophy type 1 (DM1) is a multiorgan disorder with significant cardiac involvement. ECG abnormalities, including arrhythmias, occur in 80 % of DM1 patients and are the second-most common cause of death after respiratory complications; however, the mechanisms underlying the arrhythmogenesis remain unclear. The objective of this study was to investigate the basis of the electrophysiological abnormalities in DM1 using the DMSXL mouse model.
Methods |
ECG parameters were evaluated at baseline and post flecainide challenge. Calcium transient and action potential parameters were evaluated in Langendorff-perfused hearts using fluorescence optical mapping. Calcium transient/sparks were evaluated in ventricular myocytes via confocal microscopy. Protein and mRNA levels for calcium handling proteins were evaluated using western blot and RT-qPCR, respectively.
Results |
DMSXL mice showed arrhythmic events on ECG including premature ventricular contractions and sinus block. DMSXL mice showed increased calcium transient time to peak without any change to voltage parameters. Calcium alternans and both sustained and non-sustained ventricular tachyarrhythmias were readily inducible in DMSXL mice. The confocal experiments also showed calcium transient alternans and increased frequency of calcium sparks in DMSXL cardiomyocytes. These calcium abnormalities were correlated with increased RyR2 phosphorylation without changes to the other calcium handling proteins.
Conclusions |
The DMSXL mouse model of DM1 exhibited enhanced arrhythmogenicity associated with abnormal intracellular calcium handling due to hyperphosphorylation of RyR2, pointing to RyR2 as a potential new therapeutic target in DM1 treatment.
El texto completo de este artículo está disponible en PDF.Graphical Abstract |
Highlights |
• | DM1 patients have reduced life expectancy due to cardiac causes; however, the underlying mechanisms are unclear. |
• | The DMSXL mouse model of DM1 was more prone to VTs and exhibited arrhythmic events including PVCs and sinus block. |
• | These arrhythmic events were associated with abnormal intracellular calcium transients/sparks in DMSXL mice. |
• | Our findings suggest a significant arrhythmogenic role for RyR2/phospho-RyR2, which provide novel therapeutic targets. |
Abbreviations : APD [30, 50, 80], DM1, DMPK, FCai, FCaiD80, pS2814 RyR2, NSVT, SVT, Vm, VT
Keywords : Myotonic dystrophy type 1, Ventricular tachyarrhythmia, Optical mapping, Calcium handling, DMSXL mice
Esquema
Vol 180
Artículo 117562- novembre 2024 Regresar al número
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